Exemplary embodiments relate to a semiconductor memory device, and more particularly, exemplary embodiments relate to a nonvolatile memory device and to a method of reading a nonvolatile memory device.
Non-volatile memory devices retain stored data in the absence of supplied power. Examples of non-volatile memory devices include flash memory (e.g., NAND flash and NOR flash memories), Phase change Random Access Memory (PRAM), a Magnetroresistive Random Access Memory (MRAM), a Ferroelectric Random Access Memory (FRAM), a Resistance Random Access Memory (RRAM), a Spin transfer Torque Random Access Memory (STT-RAM), and so on.
Among these, the flash memory device is a type of EEPROM (Electrically Programmable Erasable Read Only Memory) in which a plurality of memory regions are erased or programmed by one program operation. This is in contrast to a conventional EEPROM which enables only one memory region to be erased or programmed at a time. As such, systems adopting a flash memory device can operative at relatively high speeds by executing read and write operations on different memory regions simultaneously.
As mentioned above, flash memory devices are non-volatile in that they retained stored data in the absence of supplied power. That is, a flash memory device fabricated on a silicon chip retains stored information even when the supply of power to the chip is interrupted. This results in an effective means to reduce power consumption. In addition, a flash memory device exhibits a relatively high resistance to physical impact. These characteristics, together with high speed access times and the like, have resulted in the flash memory device being commonly utilized for data storage in battery-powered and portable appliances.